Stable Metal Ion Containing Compositions

ABSTRACT

Disclosed herein are oral care compositions comprising: a) one or more pyrophosphate compounds, wherein the total concentration of pyrophosphate compounds in the composition is 0.5 wt % to 1.5 wt %, based on the weight of the oral care composition; b) one or more thickening gums, wherein the total concentration of thickening gums in the composition is 1.25 wt % to 1.6 wt %, based on the weight of the oral care composition; and c) a metal ion source.

BACKGROUND

Chelating agents are sometimes used in order to reduce the metallictaste and astringency of oral care compositions containing a metal ionsource. Tetrasodium pyrophosphate (TSPP) and tetrapotassiumpyrophosphate (TKPP) are two commonly used chelating agents.

However, it has been observed that such dentifrice compositionscontaining efficacious amounts of TSPP and TKPP as chelating agentsexhibit phase separation when the dentifrice base includes certaincommonly used thickening gum systems.

A need therefore exists for metal ion-containing dentifrice compositionswhich have reduced metallic taste and astringency, and which haveimproved resistance to phase separation.

SUMMARY

A first aspect of the present invention provides an oral carecomposition comprising: (a) one or more pyrophosphate compounds, whereinthe total concentration of pyrophosphate compounds in the composition is0.5 wt % to 1.5 wt %, based on the weight of the oral care composition;(b) one or more thickening gums, wherein the total concentration ofthickening gums in the composition is 1.25 wt % to 1.6 wt %, based onthe weight of the oral care composition; and (c) a metal ion source.

Optionally, the total concentration of pyrophosphate compounds in thecomposition is 0.75 wt % to 1.25 wt %, based on the weight of the oralcare composition.

Optionally, the total concentration of pyrophosphate compounds in thecomposition is 0.9 wt % to 1.1 wt %, based on the weight of the oralcare composition.

Optionally, the one or more pyrophosphate compounds comprises dialkalimetal pyrophosphate salts, tetraalkali metal pyrophosphate salts, or anymixture of any two or more thereof.

Optionally, the one or more pyrophosphate compounds is selected fromtetrasodium pyrophosphate (TSPP), tetrapotassium pyrophosphate (TKPP),and mixtures thereof.

Optionally, the one or more pyrophosphate compounds is a mixture oftetrasodium pyrophosphate and tetrapotassium pyrophosphate.

Optionally, tetrasodium pyrophosphate is present in a concentration offrom 0.25 wt % to 0.75 wt %, based on the weight of the oral carecomposition, and tetrapotassium pyrophosphate is present in aconcentration of from 0.25 wt % to 0.75 wt % based on the weight of theoral care composition.

Optionally, the total concentration of thickening gums in thecomposition is 1.25 wt % to 1.55 wt %, based on the weight of the oralcare composition.

Optionally, the total concentration of thickening gums in thecomposition is 1.3 wt % to 1.5 wt %, based on the weight of the oralcare composition.

Optionally, the one or more thickening gums is selected fromcarboxymethyl cellulose (CMC), sodium carboxymethyl cellulose,hydroxyethyl cellulose, xanthan gum, gum arabic, gellan gum,carrageenan, gum tragacanth, guar gum, gum karaya, or any mixturethereof.

Optionally, the one or more thickening gums comprises a mixture ofcarboxymethyl cellulose and xanthan gum.

Optionally, carboxymethyl cellulose is present in a concentration of0.85 wt % to 1.2 wt % based on the weight of the oral care composition,and xanthan gum is present in a concentration of 0.4 wt % to 0.6 wt %based on the weight of the oral care composition.

Optionally, the metal ion source comprises a source of zinc ions,calcium ions, copper ions, iron ions, magnesium ions or manganese ions,or a combination of any two or more thereof.

Optionally, the metal ion source comprises a source of zinc ions.

Optionally, the source of zinc ions comprises at least one of zinccitrate, zinc lactate, zinc gluconate, zinc glycinate, zinc sulfate,zinc chloride, zinc malate, zinc tartrate, zinc carbonate, zincphosphate or zinc oxide, or any mixture thereof.

Optionally, the metal ion source is present in an amount of from 0.5 wt% to 3 wt % based on the weight of the oral care composition.

Optionally, the metal ion source is present in an amount of from 1 wt %to 2 wt % based on the weight of the oral care composition.

Optionally, the source of zinc ions comprises a mixture of zinc oxideand zinc citrate.

Optionally, zinc citrate is present in an amount of from 0.25 wt % to0.75 wt % based on the weight of the oral care composition and zincoxide is present in an amount of 0.75 wt % to 1.25 wt % based on theweight of the oral care composition.

Optionally, the composition is a dentifrice in the form of a paste orgel.

In a second aspect, the present invention provides an oral carecomposition as defined above, having improved phase separationstability.

In a third aspect, the present invention provides for use of acombination of one or more pyrophosphate compounds with one or morethickening gums to reduce or prevent phase separation of an oral carecomposition which contains a metal ion source and the at least onepyrophosphate compound, wherein the total concentration of pyrophosphatecompounds in the composition is 0.5 wt % to 1.5 wt %, based on theweight of the oral care composition and the total concentration ofthickening gums in the composition is 1.25 wt % to 1.6 wt %, based onthe weight of the oral care composition.

DETAILED DESCRIPTION

It should be understood that the detailed description and specificexamples, while indicating embodiments of the invention, are intendedfor purposes of illustration only and are not intended to limit thescope of the invention.

As used throughout, ranges are used as shorthand for describing each andevery value that is within the range. Any value within the range can beselected as the terminus of the range.

As referred to herein, all compositional percentages are by weight ofthe total composition unless otherwise indicated. As referred to herein,“ppm” (parts per million) refers to ppm by weight, unless otherwiseindicated. As referred to herein, all ratios refer to weight ratios,unless otherwise indicated.

The terms “cosmetic stability” and “phase separation stability” as usedherein refer to the ability of a dentifrice to resist phase separationinto, for example, a liquid phase and a semi-solid phase. A compositionhaving “increased phase separation stability” has an increasedresistance to phase separation.

In some embodiments, the present invention provides an oral carecomposition comprising:

-   -   a) one or more pyrophosphate compounds, wherein the total        concentration of pyrophosphate compounds in the composition is        0.5 wt % to 1.5 wt %, based on the weight of the oral care        composition;    -   b) one or more thickening gums, wherein the total concentration        of thickening gums in the composition is 1.25 wt % to 1.6 wt %,        based on the weight of the oral care composition; and    -   c) a metal ion source.

The oral care compositions of the present invention comprise one or morepyrophosphate compounds, wherein the total concentration ofpyrophosphate compounds in the composition is 0.5 wt % to 1.5 wt % basedon the weight of the oral care composition. For best taste and mouthfeel, it is desirable to maintain the total pyrophosphate compoundconcentration about 0.5 wt %.

Optionally, the total concentration of pyrophosphate compounds in thecomposition may be from 0.6 wt % to 1.4 wt %, from 0.7 wt % to 1.3 wt %,from 0.75 wt % to 1.25 wt %, from 0.8 wt % to 1.2 wt %, from 0.9 wt % to1.1 wt %, from 0.95 wt % to 1.05 wt %, or 1 wt %, all based on theweight of the oral care composition.

In some embodiments, the one or more pyrophosphate compounds comprisesdialkali metal pyrophosphate salts, tetraalkali metal pyrophosphatesalt, or any mixture of any two or more thereof.

In some embodiments, the one or more pyrophosphate compounds is selectedfrom tetrasodium pyrophosphate (TSPP), tetrapotassium pyrophosphate(TKPP), and mixtures thereof.

In some embodiments, the one or more pyrophosphate compounds is amixture of tetrasodium pyrophosphate (TSPP) and tetrapotassiumpyrophosphate (TKPP). Optionally, tetrasodium pyrophosphate is presentin a concentration of from 0.25 wt % to 0.75 wt %, based on the weightof the oral care composition, and tetrapotassium pyrophosphate ispresent in a concentration of from 0.25 wt % to 0.75 wt % based on theweight of the oral care composition. In some embodiments, TSPP ispresent in a concentration of from 0.3 wt % to 0.7 wt %, based on theweight of the oral care composition, and TKPP is present in aconcentration of from 0.3 wt % to 0.7 wt %, based on the weight of theoral care composition. In some embodiments, TSPP is present in aconcentration of from 0.4 wt % to 0.6 wt %, based on the weight of theoral care composition, and TKPP is present in a concentration of from0.4 wt % to 0.6 wt %, based on the weight of the oral care composition.In some embodiments, TSPP is present in a concentration of from 0.45 wt% to 0.55 wt %, based on the weight of the oral care composition, andTKPP is present in a concentration of from 0.45 wt % to 0.55 wt %, basedon the weight of the oral care composition. In some embodiments, TSPP ispresent in a concentration of 0.5 wt %, based on the weight of the oralcare composition, and TKPP is present in a concentration of 0.5 wt %,based on the weight of the oral care composition.

The oral care compositions of the present invention also comprise one ormore thickening gums, wherein the total concentration of thickening gumsin the composition is 1.25 wt % to 1.6 wt %, based on the weight of theoral care composition.

In some embodiments, the total concentration of thickening gums in thecomposition is 1.25 wt % to 1.55 wt %, 1.3 wt % to 1.5 wt %, 1.35 wt %to 1.45 wt %, or 1.4 wt % based on the weight of the oral carecomposition.

In some embodiments, the one or more thickening gums is selected fromcarboxymethyl cellulose (CMC), sodium carboxymethyl cellulose,hydroxyethyl cellulose, xanthan gum, gum arabic, gellan gum, carrageenan(also known as Irish moss; particularly τ-carrageenan i.e.iota-carrageenan), gum tragacanth, guar gum, gum karaya, or any mixturethereof.

In some embodiments, the one or more thickening gums comprises a mixtureof carboxymethyl cellulose and xanthan gum.

Optionally, carboxymethyl cellulose (CMC) is present in a concentrationof 0.85 wt % to 1.2 wt % based on the weight of the oral carecomposition, and xanthan gum is present in a concentration of 0.4 wt %to 0.6 wt % based on the weight of the oral care composition. In someembodiments, CMC is present in a concentration of 0.85 wt % to 1.1 wt %based on the weight of the oral care composition, and xanthan gum ispresent in a concentration of 0.45 wt % to 0.55 wt % based on the weightof the oral care composition. In some embodiments, CMC is present in aconcentration of 0.875 wt % to 1.0 wt % based on the weight of the oralcare composition, and xanthan gum is present in a concentration of 0.475wt % to 0.525 wt % based on the weight of the oral care composition. Insome embodiments, CMC is present in a concentration of 0.9 wt % based onthe weight of the oral care composition, and xanthan gum is present in aconcentration of 0.5 wt % based on the weight of the oral carecomposition.

The oral care compositions of the present invention further comprise ametal ion source. In some embodiments, the metal ion source is presentin an amount of from 0.5 wt % to 3 wt %, 0.75 wt % to 2.5 wt %, 1 wt %to 2 wt %, 1.25 wt % to 1.75 wt %, 1.3 wt % to 1.7 wt %, 1.4 wt % to 1.6wt %, 1.45 wt % to 1.55 wt %, or 1.5 wt % based on the weight of theoral care composition.

In some embodiments, the metal ion source comprises a source of zincions, calcium ions, copper ions, iron ions, magnesium ions or manganeseions, or a combination of any two or more thereof.

In some embodiments, the metal ion source comprises a source of zincions.

In some embodiments, the source of zinc ions comprises at least one ofzinc citrate, zinc lactate, zinc gluconate, zinc glycinate, zincsulfate, zinc chloride, zinc malate, zinc tartrate, zinc carbonate, zincphosphate or zinc oxide, or any mixture thereof.

In some embodiments, the source of zinc ions comprises a mixture of zincoxide (ZnO) and zinc citrate. In some embodiments, zinc citrate ispresent in an amount of from 0.25 wt % to 0.75 wt % based on the weightof the oral care composition and zinc oxide is present in an amount of0.75 wt % to 1.25 wt % based on the weight of the oral care composition.In some embodiments, zinc citrate is present in an amount of from 0.3 wt% to 0.7 wt % based on the weight of the oral care composition and zincoxide is present in an amount of 0.8 wt % to 1.2 wt % based on theweight of the oral care composition. In some embodiments, zinc citrateis present in an amount of from 0.4 wt % to 0.6 wt % based on the weightof the oral care composition and zinc oxide is present in an amount of0.9 wt % to 1.1 wt % based on the weight of the oral care composition.In some embodiments, zinc citrate is present in an amount of from 0.45wt % to 0.55 wt % based on the weight of the oral care composition andzinc oxide is present in an amount of 0.95 wt % to 1.05 wt % based onthe weight of the oral care composition. In some embodiments, zinccitrate is present in an amount of 0.5 wt % based on the weight of theoral care composition and zinc oxide is present in an amount of 1.0 wt %based on the weight of the oral care composition. In vitro biofilmreduction studies have shown that dentifrice prototypes containing 1 wt% zinc oxide and 0.5 wt % zinc citrate give particularly good bacterialkill effectiveness.

In some embodiments, the oral care composition is a dentifrice in theform of a paste or gel.

The present invention also provides an oral care composition asdescribed above having improved phase separation stability.

The present invention also provides for use of a combination of one ormore pyrophosphate compounds with one or more thickening gums to reduceor prevent phase separation of an oral care composition which contains ametal ion source and the at least one pyrophosphate compound, whereinthe total concentration of pyrophosphate compounds in the composition is0.5 wt % to 1.5 wt %, based on the weight of the oral care compositionand the total concentration of thickening gums in the composition is1.25 wt % to 1.6 wt %, based on the weight of the oral care composition.

In some embodiments, the oral care compositions of the present inventionmay comprise one or more agents selected from abrasives, diluents,bicarbonate salts, pH modifying agents, surfactants, foam modulators,additional thickening agents, viscosity modifiers, humectants,sweeteners, flavorants, pigments, antibacterial agents, anticariesagents, anticalculus or tartar control agents, and mixtures thereof.

The compositions of the present invention may include water in an amountof from about 0.5 wt % to about 25 wt %, optionally about 2.0 wt % toabout 22 wt %, further optionally about 5 wt % to about 20 wt %.

In some embodiments, the compositions of the present invention furthercomprise an abrasive.

Abrasives that may be used include silica abrasives such as precipitatedor hydrated silicas having a mean particle size of up to about 20microns, such as Zeodent 105 and Zeodent 114 marketed by J.M. HuberChemicals Division, Havre de Grace, Md. 21078, or Sylodent 783 marketedby Davison Chemical Division of W.R. Grace & Company. Abrasives such asSorbosil AC 43 from PQ Corporation may also be included. Other usefuldentifrice abrasives include aluminum oxide, aluminum silicate, calcinedalumina, bentonite or other siliceous materials, insoluble phosphates,calcium carbonate, and mixtures thereof.

The abrasive may be present in an amount of from 5 to 38 wt % based onthe weight of the composition, optionally from 10 to 20 wt % based onthe weight of the composition.

In some embodiments, the oral care compositions of the present inventioncomprise at least one bicarbonate salt, useful for example to impart a“clean feel” to teeth and gums due to effervescence and release ofcarbon dioxide. Any orally acceptable bicarbonate can be used, includingwithout limitation, alkali metal bicarbonates such as sodium andpotassium bicarbonates, ammonium bicarbonate and the like. One or morebicarbonate salts are optionally present in a total amount of about 0.1wt % to about 50 wt %, for example about 1 wt % to 20 wt %, by totalweight of the composition.

In some embodiments, the compositions of the present invention compriseat least one pH modifying agent. Such agents include acidifying agentsto lower pH, basifying agents to raise pH, and buffering agents tocontrol pH within a desired range. For example, one or more compoundsselected from acidifying, basifying and buffering agents can be includedto provide a pH of 2 to 10, or in various illustrative embodiments, 2 to8, 3 to 9, 4 to 8, 5 to 7, 6 to 10, 7 to 9, etc. Any orally acceptablepH modifying agent can be used, including without limitation,carboxylic, phosphoric and sulfonic acids, acid salts (e.g., monosodiumcitrate, disodium citrate, monosodium malate, etc.), alkali metalhydroxides such as sodium hydroxide, carbonates such as sodiumcarbonate, bicarbonates, sesquicarbonates, borates, silicates,phosphates (e.g., monosodium phosphate, trisodium phosphate), imidazoleand the like. One or more pH modifying agents are optionally present ina total amount effective to maintain the composition in an orallyacceptable pH range.

In a still further embodiment, the compositions of the inventioncomprise at least one surfactant. Any orally acceptable surfactant, mostof which are anionic, nonionic or amphoteric, can be used. Suitableanionic surfactants include without limitation, water-soluble salts ofC₈₋₂₀ alkyl sulfates, sulfonated monoglycerides of C₈₋₂₀ fatty acids,sarcosinates, taurates and the like. Illustrative examples of these andother classes include sodium lauryl sulfate, sodium coconutmonoglyceride sulfonate, sodium lauryl sarcosinate, sodium laurylisoethionate, sodium laureth carboxylate and sodium dodecylbenzenesulfonate. Suitable nonionic surfactants include withoutlimitation, poloxamers, polyoxyethylene sorbitan esters, fatty alcoholethoxylates, alkylphenol ethoxylates, tertiary amine oxides, tertiaryphosphine oxides, dialkyl sulfoxides and the like. Suitable amphotericsurfactants include without limitation, derivatives of C₈₋₂₀ aliphaticsecondary and tertiary amines having an anionic group such ascarboxylate, sulfate, sulfonate, phosphate or phosphonate. Betaines mayalso be used, a suitable example of which is cocoamidopropyl betaine.One or more surfactants are optionally present in a total amount ofabout 0.01 wt % to about 10 wt %, for example, from about 0.05 wt % toabout 5 wt %, or from about 0.1 wt % to about 2 wt % by total weight ofthe composition.

In some embodiments, the compositions of the invention comprise at leastone foam modulator, useful for example to increase amount, thickness orstability of foam generated by the composition upon agitation. Anyorally acceptable foam modulator can be used, including withoutlimitation, polyethylene glycols (PEGs), also known as polyoxyethylenes.High molecular weight PEGs are suitable, including those having anaverage molecular weight of 200,000 to 7,000,000, for example 500,000 to5,000,000, or 1,000,000 to 2,500,000. One or more PEGs are optionallypresent in a total amount of about 0.1 wt % to about 10 wt %, forexample from about 0.2 wt % to about 5 wt %, or from about 0.25 wt % toabout 2 wt %, by total weight of the composition.

In some embodiments, the compositions of the present invention compriseat least one additional thickening agent, useful for example to impart adesired consistency and/or mouth feel to the composition. Any orallyacceptable thickening agent can be used, including without limitation,carbomers, also known as carboxyvinyl polymers, colloidal magnesiumaluminum silicate, colloidal silica and the like. A preferred class ofadditional thickening or gelling agents includes a class of homopolymersof acrylic acid crosslinked with an alkyl ether of pentaerythritol or analkyl ether of sucrose, or carbomers. Carbomers are commerciallyavailable from B. F. Goodrich as the Carbopol® series. Particularlypreferred Carbopols include Carbopol 934, 940, 941, 956, 974P, andmixtures thereof. Silica thickeners such as DT 267 (from OSC-LianjiChemical Industry Co., Ltd.) may also be used. One or more additionalthickening agents are optionally present in a total amount of from about0.01 wt % to 15 wt %, for example from about 0.1 wt % to about 10 wt %,or from about 0.2 wt % to about 5 wt %, by total weight of thecomposition.

In some embodiments, the compositions of the invention comprise at leastone viscosity modifier, useful for example to help inhibit settling orseparation of ingredients or to promote re-dispersibility upon agitationof a liquid composition. Any orally acceptable viscosity modifier can beused, including without limitation, mineral oil, petrolatum, clays andorganomodified clays, silica and the like. One or more viscositymodifiers are optionally present in a total amount of from about 0.01 wt% to about 10 wt %, for example, from about 0.1 wt % to about 5 wt %, bytotal weight of the composition.

In some embodiments, the compositions of the invention comprise at leastone humectant. Any orally acceptable humectant can be used, includingwithout limitation, polyhydric alcohols such as glycerin, sorbitol(particularly as a 70% solution), xylitol or low molecular weightpolyethylene glycols (PEGs). Most humectants also function assweeteners. One or more humectants are optionally present in a totalamount of from about 1 wt % to about 70 wt %, for example, from about 1wt % to about 50 wt %, from about 2 wt % to about 25 wt %, or from about5 wt % to about 15 wt %, by total weight of the composition.

In some embodiments, a composition of the present invention comprises atleast one sweetener, useful for example to enhance taste of thecomposition. Any orally acceptable natural or artificial sweetener canbe used, including without limitation dextrose, sucrose, maltose,dextrin, dried invert sugar, mannose, xylose, ribose, fructose,levulose, galactose, corn syrup (including high fructose corn syrup andcorn syrup solids), partially hydrolyzed starch, hydrogenated starchhydrolysate, sorbitol, mannitol, xylitol, maltitol, isomalt, aspartame,neotame, saccharin and salts thereof (such as sodium saccharin),dipeptide-based intense sweeteners, cyclamates and the like. One or moresweeteners are optionally present in a total amount depending stronglyon the particular sweetener(s) selected, but typically 0.005 wt % to 5wt %, by total weight of the composition, optionally 0.005 wt % to 0.2wt %, further optionally 0.05 wt % to 0.1 wt % by total weight of thecomposition.

In some embodiments, a composition of the present invention comprises atleast one flavorant, useful for example to enhance taste of thecomposition. Any orally acceptable natural or synthetic flavor can beused, including without limitation tea flavours (such as Cool JasmineTea Flavour), vanillin, sage, marjoram, parsley oil, spearmint oil,cinnamon oil, oil of wintergreen (methylsalicylate), peppermint oil,clove oil, bay oil, anise oil, eucalyptus oil, citrus oils, fruit oilsand essences including those derived from lemon, orange, lime,grapefruit, apricot, banana, grape, apple, strawberry, cherry,pineapple, etc., bean- and nut-derived flavors such as coffee, cocoa,cola, peanut, almond, etc., and other flavours; adsorbed andencapsulated flavorants and the like. Also encompassed within flavorantsherein are ingredients that provide fragrance and/or other sensoryeffect in the mouth, including cooling or warming effects. Suchingredients illustratively include menthol, menthyl acetate, menthyllactate, camphor, eucalyptus oil, eucalyptol, anethole, eugenol, cassia,oxanone, α-irisone, propenyl guaiethol, thymol, linalool, benzaldehyde,cinnamaldehyde, N-ethyl-p-menthan-3-carboxamine,N,2,3-trimethyl-2-isopropylbutanamide, 3-(1-menthoxy)-propane-1,2-diol,cinnamaldehyde glycerol acetal (CGA), menthone glycerol acetal (MGA) andthe like. One or more flavorants are optionally present in a totalamount of from about 0.01 wt % to about 5 wt %, for example, from about0.03 wt % to about 2.5 wt %, optionally about 0.05 wt % to about 1.5 wt%, further optionally about 0.1 wt % to about 0.3 wt % by total weightof the composition.

A composition of the invention may comprise at least one colorant.Colorants herein include pigments, dyes, lakes and agents imparting aparticular luster or reflectivity such as pearling agents. Any orallyacceptable colorant can be used, including without limitation talc,mica, magnesium carbonate, calcium carbonate, magnesium silicate,magnesium aluminum silicate, silica, titanium dioxide, zinc oxide, red,yellow, brown and black iron oxides, ferric ammonium ferrocyanide,manganese violet, ultramarine, titaniated mica, bismuth oxychloride,Blue#1 1.25% solution, and the like. One or more colorants areoptionally present in a total amount of from about 0.001 wt % to about20 wt %, for example, from about 0.01 wt % to about 10 wt %, or fromabout 0.1 wt % to about 5 wt %, by total weight of the composition.

The compositions of the present invention optionally comprise anantibacterial or preservative agent, such as chlorhexidine, triclosan,quaternary ammonium compounds (for example benzalkonium chloride) orparabens such as methylparaben or propylparaben. One or moreantibacterial or preservative agent is optionally present in thecomposition in a total amount of from about 0.01 wt % to about 0.5 wt %,optionally about 0.05 wt % to about 0.1 wt % by total weight of thecomposition.

In some embodiments, the composition comprises a fluoride ion source.Fluoride ion sources include, but are not limited to: stannous fluoride,sodium fluoride, potassium fluoride, potassium monofluorophosphate,sodium monofluorophosphate, ammonium monofluorophosphate, sodiumfluorosilicate, ammonium fluorosilicate, amine fluoride such as olaflur(N′-octadecyltrimethylendiamine-N,N,N′-tris(2-ethanol)-dihydrofluoride),ammonium fluoride, and combinations thereof. In certain embodiments thefluoride ion source includes stannous fluoride, sodium fluoride, aminefluorides, sodium monofluorophosphate, as well as mixtures thereof. Incertain embodiments, the oral care composition of the invention may alsocontain a source of fluoride ions or fluorine-providing ingredient inamounts sufficient to supply about 50 to about 5000 ppm fluoride ion,e.g., from about 100 to about 1000, from about 200 to about 500, orabout 250 ppm fluoride ion. Fluoride ion sources may be added to thecompositions of the invention at a level of about 0.001 wt % to about 10wt %, e.g., from about 0.003 wt % to about 5 wt %, 0.01 wt % to about 1wt, or about 0.05 wt %. However, it is to be understood that the weightsof fluoride salts to provide the appropriate level of fluoride ion willobviously vary based on the weight of the counter ion in the salt, andone of skill in the art may readily determine such amounts. A preferredfluoride salt may be sodium fluoride.

Some embodiments of the present invention provide compositions having anN value of less than 1.5. Other embodiments provide compositions havingan N value less than 1. Further embodiments provide compositions havingan N value of less than 0.5. Yet other embodiments provide compositionshaving an N value of less than 0.1.

The composition of the present invention optionally comprises a salivastimulating agent useful, for example, in amelioration of dry mouth. Anyorally acceptable saliva stimulating agent can be used, includingwithout limitation food acids such as citric, lactic, malic, succinic,ascorbic, adipic, fumaric and tartaric acids, and mixtures thereof. Oneor more saliva stimulating agents are optionally present in salivastimulating effective total amount.

The composition of the present invention optionally incorporates one ormore antisensitivity agents, e.g., potassium salts such as potassiumnitrate, potassium bicarbonate, potassium chloride, potassium citrate,and potassium oxalate; capsaicin; eugenol; strontium salts; chloridesalts and combinations thereof. Such agents may be added in effectiveamounts, e.g., from about 1 wt % to about 20 wt % by weight based on thetotal weight of the composition, depending on the agent chosen. Thecompositions of the present invention may also be used to treathypersensitivity by blocking dentin tubules when applied to a tooth.

In some embodiments, the composition of the invention further comprisesan antioxidant. Any orally acceptable antioxidant can be used, includingbutylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), vitaminA, carotenoids, vitamin E, flavonoids, polyphenols, ascorbic acid,herbal antioxidants, chlorophyll, melatonin, and mixtures thereof.

The composition of the present invention may additionally optionallycomprise a tartar control (anticalculus) agent as provided below. Tartarcontrol agents among those useful herein include salts of the specifiedagents, including alkali metal and ammonium salts. The agents include:phosphates and polyphosphates, polyaminopropanesulfonic acid (AMPS),polyolefin sulfonates, polyolefin phosphates, diphosphonates such asazacycloalkane-2,2-diphosphonates (e.g.,azacycloheptane-2,2-diphosphonic acid), N-methylazacyclopentane-2,3-diphosphonic acid, ethane-1-hydroxy-1,1-diphosphonicacid (EHDP) and ethane-1-amino-1,1-diphosphonate, phosphonoalkanecarboxylic acids and. Useful inorganic phosphate and polyphosphate saltsinclude monobasic, dibasic and tribasic sodium phosphates, sodiumtripolyphosphate, tetrapolyphosphate, sodium trimetaphosphate, sodiumhexametaphosphate and mixtures thereof. Other useful tartar controlagents include polycarboxylate polymers and polyvinyl methylether/maleic anhydride (PVM/MA) copolymers, such as GANTREZ®.

In some embodiments, the composition of the present invention furthercomprises a nutrient. Suitable nutrients include vitamins, minerals,amino acids, and mixtures thereof. Vitamins include Vitamins C and D,thiamine, riboflavin, calcium pantothenate, niacin, folic acid,nicotinamide, pyridoxine, cyanocobalamin, para-aminobenzoic acid,bioflavonoids, and mixtures thereof. Nutritional supplements includeamino acids (such as L-tryptophan, L-lysine, methionine, threonine,levocarnitine and L-carnitine), lipotropics (such as choline, inositol,betaine, and linoleic acid), and mixtures thereof.

For a dentifrice composition containing 1 wt % zinc oxide and 0.5 wt %zinc citrate, the addition of 1 wt % TSPP and 1 wt % TKPP has beenperceived to improve taste and mouthfeel. A combination of CMC andxanthan gum in concentrations of 0.8 wt % and 0.3 wt %, respectively, iscommonly used in dentifrice compositions in order to provide structureand desired aesthetics to the composition. However, the presentinventors have observed that, in a dentifrice composition which contains1 wt % zinc oxide and 0.5 wt % zinc citrate in combination with 1 wt %TSPP and 1 wt % TKPP, phase separation occurs immediately afterformation of the dentifrice composition if the commonly-used thickeningsystem of 0.8 wt % CMC and 0.3 wt % xanthan gum is employed, in a highsorbitol silica formula. This separation was observed to become moresevere during aging at both 40° C. and −10° C.

Without wishing to be bound by any theory, it is thought that therelatively high level of 2 wt % total pyrophosphate compounds isresponsible for disrupting the structure of the dentifrice, and that thethickening system of 0.8 wt % CMC and 0.3 wt % xanthan gum does notprovide enough structure to maintain the dentifrice in a single phase.However, as will be discussed below, the present inventors have foundthat simply increasing the concentration of the gums alone did notimprove the phase separation stability; and that simply decreasing theconcentration of the pyrophosphates alone also did not improve the phaseseparation stability. In fact, the present inventors have found thatsimply increasing the gum concentration or decreasing the pyrophosphateconcentration alone further decreased the phase separation stability.However, the present inventors have surprisingly found that increasingthe gum concentration together with decreasing the pyrophosphateconcentration actually increased the phase separation stability of thedentifrice compositions.

EXAMPLES

A series of studies showed that a marked improvement in phase separationstability could be achieved if the total concentration of carboxymethylcellulose and xanthan gum in an oral care composition was increased from1.1 wt % to 1.4 wt %, and if the total concentration of tetrasodiumpyrophosphate and tetrapotassium pyrophosphate in the composition wassimultaneously decreased from 2 wt % to 1.5 wt %. The studies showedthat, while the phase separation stability was drastically improved, thetaste and mouth feel of the composition remained acceptable.

Formulations A to E were prepared, as detailed in Table 1, below. Ofthese, Formulation A corresponds to the original formula containing 1 wt% TKPP, 1 wt % TSPP, 0.8 wt % carboxymethyl cellulose (CMC) and 0.3 wt %xanthan gum. In Formulation B, the concentration of TKPP and TSPP werekept the same as in Formulation A, but the concentration of CMC wasincreased to 0.9 wt % and the concentration of xanthan gum was increasedto 0.5 wt %. In Formulation C, the concentration of xanthan gum and CMCwas kept the same as in Formulation A, but the concentrations of TKPPand TSPP were reduced to 0.7 wt % and 0.5 wt %, respectively. InFormulations D and E, the concentrations of TKPP and TSPP were eachreduced to 0.5 wt % and the concentrations of CMC and xanthan gum wereincreased to 0.9 wt % and 0.5 wt %, respectively.

TABLE 1 A B C D E (wt %) (wt %) (wt %) (wt %) (wt %) Water 13.3 13 14.114.1 14 Sorbitol - 70% solution 55 55 55 55 55 Polyethylene Glycol 600 22 2 2 2 Sodium saccharin 0.3 0.3 0.3 0.3 0.3 AC 43 abrasive 5 5 5 5 5ZnO 1 1 1 1 1 Zinc Citrate 0.5 0.5 0.5 0.5 0.5 TSPP 1 1 0.7 0.5 0.5 TKPP1 1 0.5 0.5 0.5 CMC 2000S 0.8 0.9 0.8 0.9 0.9 Xanthan Gum 0.3 0.5 0.30.5 0.5 Sodium 1.1 1.1 1.1 1.1 1.1 monofluorophosphate Silica abrasiveZeo 114 10 10 10 10 10 Silica thickener DT 267 4 4 4 4 4 Sodium laurylsulfate 2 2 2 2 2 Cocamidopropyl betaine 1.25 1.25 1.25 1.25 1.25 Flavor1 1.3 1.3 1.3 — 1.3 Flavor 2 — — — 1.2 — Blue #1 - 1.25% solution 0.150.15 0.15 0.15 0.15 TOTAL 100 100 100 100 100

Phase separation of a composition can be predicted using acentrifugation method. Samples are centrifuged using an analyticalcentrifuge (LumiSizer 110 from L.U.M. GmbH, Berlin), which measuresseparation of the product by measuring optical transmission through thetube as a function of time. The centrifugation method generates a numberknown as the “wall liquid separation scale number”, N. Sample stabilityis considered as acceptable when N≤3 and unacceptable when N>3. Thelower the N value, the more robust the formula (i.e. the higher itsresistance to phase separation). Most often, a value of N which is lessthan 1.5 is necessary to ensure a greater confidence in predicting realtime stability.

The centrifugation method was used to predict the likelihood of phaseseparation for each of the formulations A to E above for 3 years shelflife at ambient temperature. The wall liquid separation scale number wascalculated for each of these formulations, and the results are shownbelow in Table 2 (below):

TABLE 2 A B C D E (wt %) (wt %) (wt %) (wt %) (wt %) Wall separationscale 1.94 3.55 3.72 0.07 0.07 number, N

As can be seen in Table 2, simply increasing the concentration of thethickening gum (Formulation B) or simply decreasing the concentration ofthe pyrophosphates (Formulation C) as compared to the originalFormulation A in fact decreased the phase separation stability of thecompositions (as shown by the increase in N value for Formulations B andC as compared to Formulation A). This high N value for Formulations Band C indicates that these compositions will phase separate and resultin a product which is not shelf stable.

However, both Formulations D and E (in which the concentration ofthickening gum was increased and the concentration of pyrophosphates wasdecreased as compared to Formulation A) have a very low wall separationscale number of N=0.07, indicating that these formulations will providean acceptable level of phase separation.

A real-time accelerated aging study of Formulation D and E showed thatthere was no phase separation of these compositions for up to 6 months,confirming the prediction of the centrifugation method. In contrast,Formulation A failed the real-time accelerated aging test.

It was also found that the taste and mouth feel of the compositionscontaining a total concentration of 1.4 wt % CMC and xanthan gum, and atotal concentration of 1.5 wt % TSPP and TKPP were acceptable.

Whilst particular embodiments of the invention have been illustrated anddescribed, it will be obvious to those skilled in the art that variouschanges and modifications may be made without departing from the scopeof the invention as defined in the appended claims.

What is claimed is:
 1. An oral care composition comprising: a) one ormore pyrophosphate compounds, wherein the total concentration ofpyrophosphate compounds in the composition is 0.9 wt % to 1.1 wt %, ofthe composition; b) one or more thickening gums, wherein the totalconcentration of thickening gums in the composition is 1.25 wt % to 1.6wt %, of the composition; and c) a metal ion source.
 2. The compositionaccording to claim 1, wherein the one or more pyrophosphate compoundscomprises a dialkali metal pyrophosphate salt, a tetraalkali metalpyrophosphate salt, or a combination thereof.
 3. The compositionaccording to claim 2, wherein the one or more pyrophosphate compounds isselected from tetrasodium pyrophosphate (TSPP), tetrapotassiumpyrophosphate (TKPP), and a combination thereof.
 4. The compositionaccording to claim 3, wherein the one or more pyrophosphate compounds isa mixture of tetrasodium pyrophosphate and tetrapotassium pyrophosphate.5. The composition according to claim 4, wherein tetrasodiumpyrophosphate is present in a concentration of from 0.25 wt % to 0.75 wt%, based on the weight of the oral care composition, and tetrapotassiumpyrophosphate is present in a concentration of from 0.25 wt % to 0.75 wt% based on the weight of the oral care composition
 6. The compositionaccording to claim 1, wherein the total concentration of thickening gumsin the composition is 1.25 wt % to 1.55 wt %, based on the weight of theoral care composition.
 7. The composition according to claim 6, whereinthe total concentration of thickening gums in the composition is 1.3 wt% to 1.5 wt %, based on the weight of oral care composition.
 8. Thecomposition according to claim 1, wherein the one or more thickeninggums is selected from carboxymethyl cellulose (CMC), sodiumcarboxymethyl cellulose, hydroxyethyl cellulose, xanthan gum, gumarabic, gellan gum, carrageenan, gum tragacanth, guar gum, gum karaya,or any mixture thereof.
 9. The composition according to claim 8, whereinthe one or more thickening gums comprises a mixture of carboxymethylcellulose and xanthan gum.
 10. The composition according to claim 9,wherein carboxymethyl cellulose is present in a concentration of 0.85 wt% to 1.2 wt % based on the weight of the oral care composition, andxanthan gum is present in a concentration of 0.4 wt % to 0.6 wt % basedon the weight of the oral care composition.
 11. The compositionaccording to claim 1, wherein the metal ion source comprises a source ofzinc ions, calcium ions, copper ions, iron ions, magnesium ions ormanganese ions, or a combination of two or more thereof.
 12. Thecomposition according to claim 11, wherein the metal ion sourcecomprises a source of zinc ions.
 13. The composition according to claim12, wherein the source of zinc ions comprises at least one of zinccitrate, zinc lactate, zinc gluconate, zinc glycinate, zinc sulfate,zinc chloride, zinc malate, zinc tartrate, zinc carbonate, zincphosphate or zinc oxide, or any mixture thereof.
 14. The compositionaccording to claim 1, wherein the metal ion source is present in anamount of from 0.5 wt % to 3 wt % based on the weight of the oral carecomposition.
 15. The composition according to claim 14, wherein themetal ion source is present in an amount of from 1 wt % to 2 wt % basedon the weight of the oral care composition.
 16. The compositionaccording to claim 13, wherein the source of zinc ions comprises amixture of zinc oxide and zinc citrate.
 17. The composition according toclaim 16, wherein zinc citrate is present in an amount of from 0.25 wt %to 0.75 wt % based on the weight of the oral care composition and zincoxide is present in an amount of 0.75 wt % to 1.25 wt % based on theweight of the oral care composition.
 18. The composition according toclaim 1, wherein the composition is a dentifrice in the form of a pasteor gel.
 19. The composition according to claim 1, having improved phaseseparation stability.
 20. The composition according to claim 1, whereinthe ratio of pyrophosphate compounds to thickening gums is less than1:1.
 21. The composition according to claim 1, wherein the ratio ofpyrophosphate compounds to thickening gums is less than 0.99.
 22. Thecomposition according to claim 1, wherein the ratio of pyrophosphatecompounds to thickening gums is less than 0.8.
 23. The compositionaccording to claim 1, wherein the ratio of pyrophosphate compounds tothickening gums is less than 0.75.
 24. The composition according toclaim 1, wherein the N value is less than 1.5.
 25. (canceled)